Air gun or air pistol



Sept. 14, 1965 Y A. G. METCALF 3,205,883

AIR GUN 0R AIR PISTOL Filed March 7, 1965 3 Sheets-Sheet 1 \NVENTOR A G. Metca l f ATTQRNEY Sept. 14, 1965 A. G. METCALF AIR GUN OR AIR PISTOL 3 Sheets-Sheet 2 Filed March 7, 1963 INVENTOR A G Mefca/f ATTORNEY Sept. 14, 1965 A. G. METCALF AIR GUN 0R AIR PISTOL 3 Sheets-Sheet 3 Filed March 7, 1963 INVENTOR A. G. Mei-calf BY A-r'rog gl United States Patent 3,205,883 AIR GUN 0R AIR PISTOL Alfred Guest Metcalf, Edinburgh, Scotland, assignor to Millard Brothers Limited, London, England, a British company Filed Mar. 7, 1963, Ser. No. 263,471 Claims priority, application Great Britain, Mar. 12, 1962, 9,479/ 62 3 Claims. (Cl. 124-15) This invention relates to air guns or air pistols of the type hereinafter referred to as the type specified, wherein a pellet, dart or the like is propelled from the gun barrel by compressed air produced by a piston which on release of a trigger, is driven forward towards the end of an air cylinder by a spring, so as to compress the air in front of the piston and force it into the breech end of the gun barrel through an aperture in a member located at the breech end of the gun barrel and extending transversely thereof.

Where there are relatively movable parts between the adjacent ends of the barrel and air cylinder, it is virtually impossible to prevent the escape of some of the compressed air along the surfaces of such parts with the result that there will be a loss of effective power for firing the pellet or dart. This drawback applies particularly to what is known as the under-lever cocking type of gun. Where the relatively movable parts are in metal to metal contact, the leakage of air will increase as the parts become worn in use.

It is an object of the present invention to provide means for overcoming this drawback.

According to the present invention, an air gun or air pistol has auxiliary sealing means in the air cylinder adjacent the breech end thereof, the auxiliary sealing means having an axial passage for the flow of compressed air upon firing the weapon and being urged by the flow of compressed air to provide an air seal between the wall of the air cylinder and the adjacent part of the weapon.

The auxiliary sealing means may take the form of an axially bored piston with its axis aligned with the axis of the barrel, preferably having an annular sealing washer on its forward end around the bore, and being a longitudinally sliding fit in a chamber at the forward end of the air cylinder. This piston is capable of rearward motion so that when the gun is being cocked the suction in the main cylinder withdraws the sealing piston from the face of the breech plate.

Preferably the piston is capable of rearward motion while the gun is being cocked.

Alternatively, the auxiliary sealing means may comprise a flexible annular washer mounted transversely in the air cylinder, the arrangement being such that the inner edge of the forward surface of the washer is urged into contact with the adjacent part of the weapon by the flow of compressed air when the weapon is fired.

To enable the invention to be fully understood, it will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a sectional fragmentary view of part of an air gun according to one embodiment of the invention, the parts being shown in cocked position; and

FIGURE 2 is a similar view but showing the parts in position after the gun has been fired;

FIGURE 3 is a fragmentary sectional side view of part of an air gun according to a second embodiment of the invention, the parts being shown in cocked position;

FIGURE 4 is a fragmentary plan view corresponding to FIGURE 3;

FIGURE 5 is a fragmentary sectional side view of the embodiment of FIGURE 3, the parts being shown in the "ice positions they occupy as the main piston finishes its forward travel;

FIGURE 6 is a fragmentary plan view corresponding to FIGURE 5.

As shown in FIGURES 1 and 2 of the accompanying drawings, 1 indicates the gun barrel and Z the air cylinder in which a main piston 3 is slidably mounted. A cocking lever 4 is pivoted at 5 and pivotally connected to a link 6 having a nose 7 slidable in a slot in a rearward extension of the air cylinder in which a spring 8 is housed. It will be understood that when the lever 4 is pivoted from the position shown in FIGURE 2 to the position shown in FIGURE 1, the main piston 3 will be moved rearwardly to compress the spring 8, and retained in rearward position by latch means releasable by the gun trigger in known manner.

A cylindrical chamber 9 is provided at the forward or breech end of the cylinder 2, and an auxiliary piston 10 having an axial bore 11 is slidably mounted in the chamber 9. The piston 10 is a close fit in the chamber and has an annular washer 12 of rubber, neoprene or like resilient material at the forward or breech end so as to surround the open end of the bore 11. Alternatively, experiments have shown that the neoprene or resilient washer can be eliminated and replaced by suitable metal to metal contact.

A breech plate 13 having a pellet receiving aperture 14 is slidably mounted in the space between the breech end of the barrel 1 and the cylinder 2, the breech plate being connected by a link 15 with the lever 4 that when the lever is moved into cooking position, as indicated in FIGURE 1, the plate 13 is raised to enable a pellet to be inserted by hand or automatically from a magazine into the aperture 14, and when the lever is returned to its forward position the plate is lowered to position the pellet in the aperture in alignment with the breech end of the barrel 1.

It will be noted from FIGURE 1 that the washer 12 is spaced from the plate 13 so that the movement of the plate is unrestricted. When, however, the gun trigger (not shown) is pulled to release the latch holding the main piston 3, the latter is driven forward by the spring 8 to compress the air in the cylinder 2. Immediately the main piston 3 starts to move forward the air will be compressed sufficiently to effect the outward movement of the auxiliary piston 10 to force the washer 12 or steel sealing face into sealing engagement with the breech plate 13 and so prevent the escape of air over the plate and laterally outwards of the gun. Accordingly, the whole of the compressive force of the air in the cylinder 2 is discharged into the barrel for propelling the pellet.

When the gun is re-cocked, thesuction created in the cylinder 2 by the rearward movement of the piston 3 will serve to draw the auxiliary piston inwardly a short distance away from the breech plate, as indicated in FIGURE 1.

The axial movement of the auxiliary piston enables it automatically to compensate for any wear of the surface of the breech plate.

If desired, the auxiliary piston may be adapted, as it is moved outwardly into sealing engagement, to engage and displace the pellet from the aperture 14 into the breech end of the barrel.

The auxiliary piston may be made of metal and provided with rings of rubber or neoprene 10a for making sliding engagement with the wall of the chamber 9, and improving the fit of the auxiliary piston. Alternatively, the piston may be made of rubber or similar resilient material which will expand into the chamber 9 when air pressure is created in the main cylinder 2.

In the second embodiment, shown in FIGURES 36, the place of the auxiliary piston is taken by a flexible diaphragm.

In this embodiment, the breech plate is of a horizontally moving cam-operated type.

As in the first embodiment, the gun illustrated in FIGURES 3 to 6 has a barrel 1, an air cylinder 2, a piston 3 sliding in cylinder 2, a cocking lever 4 pivoted to the gun at 5, and also to a link 6 having a nose 7 which slides in a slot in cylinder 2. A main spring 8 is provided to drive the main piston when the gun is fired.

At the front end of the cylinder 2, however, the bore 9 is provided with two closely spaced annular lands 9a between which is fitted an annular washer 20 of resilient synthetic material. This diaphragm has an axial hole 11 which tapers towards the front of the gun.

A breech plate 13, with an aperture 14, slides in a horizontal direction in a downwardly open slot in the gun body. Projecting downwardly from the plate 13 is the head of a bolt 15a which engages in a curved cam slot 16 in a cam plate 17.

In use, the lever 4 is swung rearwardly about the pivot 5, thus forcing the piston 3 back against the spring 8, and also pushing the cam plate 17 into its rearward position. This movement of the plate 17 causes the bolt 15a to move from right to left of the gun as constrained by slot 16, moving the breech plate to expose the aperture 14. A pellet is placed in aperture 14, and the lever 4 is swung forwardly until it lies against the barrel 1. The nose 7 therefore pulls the cam plate 17 into its forward position and the curvature of slot 16 causes the breech plate to move from left to right of the gun as bolt 15a tracks in slot 16, When the lever 4 is in its final position, aperture 14 is aligned with the bore of the barrel 1. On releasing piston 3 by a trigger (not shown), to fire the gun, the flow of compressed air will distort the diaphragm 20 into the position shown in FIGURE 5, thus forming a seal between the wall of cylinder 2 and the breech plate 13. Thus, as soon as sufficient pressure is built up to produce this distortion, no further air will leak out along the rear surface of the breech plate during that stroke of the piston.

As soon as piston 3 comes to rest, the diphragm is no longer urged against the breech plate, so that when the gun is re-cocked, there is noabrading pressure between the diphragm and the breech plate. Should there be any sticking between the two parts which is not overcome by resilience of the diaphragm, the reverse flow of air as piston 3 moves back should blow the diaphragm off the plate.

It will be understood that instead of sliding breech plates as illustrated herein, it is equally possible to use breech plates of the rotating or swinging type, or to provide a colt type rotating breech chamber. Also the supplementary piston may be taken out of sealing contact by mechanical means.

The invention is not, however, limited to guns or pistols having breech plates or chambers, as the auxiliary piston or the like could be adapted to make sealing engagement with the breech end of the barrel.

I claim: 1

1. In an air gun of the type comprising a cylinder defining an air chamber, a firing piston in said air chamber and an apertured transverse member located at the forward end of the said air chamber and defining the breech end thereof, the improvement which comprises sealing means located in the air chamber adjacent said transverse member having an aperture aligned with the aperture in said transverse member, said sealing means being independent of the firing piston and movable by the pressure of the air produced in the air chamber by the firing piston to make annular sealing engagement with portions of the transverse member surrounding the aperture in the latter.

2. In an air gun of the type comprising a cylinder defining an air chamber, a firing piston in said air chamber and an apertured transverse member located at the forward end of the said air chamber and defining the breech end thereof, the improvement which comprises an axially bored auxiliary piston making an air-tight sliding fit in the said air chamber adjacent said transverse member, an annular resilient sealing ring carried by said auxiliary piston, said auxiliary piston being movable by the pressure of the air produced in the air chamber by the said firing piston to urge said resilient sealing ring into resilient annular sealing engagement with said transverse member around the aperture in the latter.

3. In an air gun of the type comprising a cylinder defining an air chamber, a firing piston in said air chamher and an apertured transverse member located at the forward end of the said air chamber and defining the breech end thereof, the improvement which comprises an annular groove in the inner peripheral wall of said air chamber adjacent said transverse member, a flexible annular washer mounted in the air chamber, said washer having an outer peripheral edge secured in said groove and a free inner peripheral edge movable by the pressure of the air produced in the air chamber by the firing piston into annular sealing engagement with said transverse member around the aperture in the latter.

References Cited by the Examiner UNITED STATES PATENTS 1,869,600 8/32 Loomis 124-15 FOREIGN PATENTS 799,805 8/58 Great Britain.

RICHARD C. PINKHAM, Primary Examiner, 

1. IN AN AIR GUM OF THE TYPE COMPRISING A CYLINDER DEFINING AN AIR CHAMBER, A FIRING PISTION IN SAID AIR CHAMBER AND AN APERTURED TRANSVERSE MEMBER LOCATED AT THE BREECH END THEREOF, THE IMPROVEMENT WHICH COMPRISES BRREECH END THEREOF, THE IMPROVEMENT WHICH COMPRISES SEALING MEANS LOCATED IN THE AIR CHAMBER ADJACENT ADJACENT TRANSVERSE MEMBER HAVING AN APERTURE ALIGNED WITH THE APERTURE IN SAID TRANSVERSE MEMBER, SAID SEALING MEANS BEING INDEPENDENT OF THE FIRING PISTON AND MOVABLE BY THE PRESSURE OF THE AIR PRODUCED IN THE AIR CHAMBER BY THE FIRING PISTON TO MAKE ANNULAR SEALING ENGAGEMENT WITH PORTIONS OF THE TRANSVERSE MEMBER SURROUNDING THE APERATURE IN THE LATTER. 